Process for cooling molten bitumen



y 5, 1932- KIRSCHBRAUN v 1,866,504

PROCESS FOR COOLING HOLTEN BITUMEN Filed ma 29. 1930 v 3 m2 H5 I; fl

Patented July '5, 1932 i UNITED STATES PATENTO'FFICE- LESTER'KIRSCHBItAUN, OF LEONLA, NEW JERSEY PROCESS FOR COOLING MOLTEN IBITUMENv Application filed May 29,

This invention relates to improvements in the production of aqueousbltumlnous emulsions, and is more particularly concerned withimprovements in the production of aqueous dispersions-of the typedisclosed in my prior Patent No. 1,615,303, granted J aning the same toagitation in the presence of Y such for example as colloidal clay,

"that the temperature of an aqueous suspension of colloidal materialunder conditions which serve to induce and promote rapid attenuation ofthe bitumen into threads and subdivisionthereof into finely dividedparticles dispersed in the aqueous vehicle. The colloidal material whichmay be employed in carrying out a process of the character described maycomprise any one of a class of materials which are readily wet withwater and capable of forming a viscous plastic mass therewith,bentonite, mineral pigments, slate dust, powdered mefalilic oxides,"hydroxides and silicates or the In the commercial manufacture 'ofaqueous bituminous emulsions of the type set forth it is essential thatthe bath of material in which the dispersion'is-being effected, bemaintained at suitably controlled temperatures such as will provide amedium of sufficient viscosity to produce that degree of nternalviscosity which is necessary to effect largely upon the character ofbitumen being,

emulsified, but in general it may be stated the bath should approximatethe, melting point of the bitumen and at all events not more thanaproximately 10 F. above the melting point thereof.

In the commercial'pract-ice of the process set forth in said patent, thetemperature of the bath may be maintained at a suitable point byproviding the emulsifying vessel with jackets forcirculating atemperature 1930. Serial No. 456,952.

regulating medium and/or by adding water frlom time to time to thematerial in the vesse I have found in actual practice that it is quitediflicult to maintain at all times the proper conditions of temperaturein the emulsifying vessel, when the asphalt or other material tobe'emulsified is fed in heat liquefied condition directly to theemulsifying vessel at a temperature considerably above the temperatureof the mass in the vessel. Under these conditions, particularly when theasphalt is fed at a rapid rate, it frequently happens that localcoalescence of emulsified particles occurs in the vessel where the hotmolten asphalt strikes the material therein, causing considerableagglomeration of these emulsified particles, which must be overcome byadditions of substantial quantities of water, thus resulting in theproduction of an emulsion containing more than the optimum amount ofwater in the external phase. It will be appreciated, of course, that itis desirable to produce an emulsion ,containing a minimum quantityofwater in the external phase for any degree of dispersion, consistentwith suspendable product.

According to my present invention, the con trol of temperature isfacilitated, the production rate increased and the process other- 30wise improved by the provision of a cooling stage for the molten asphaltimmediately prior to its introduction into the emulsifyinginstrumentality, such that the asphalt may be reduced to a temperatureabout 50- degrees 35 otherwise improving upon the commercial manufactureof this type of emulsion. This difi'erential of, temperature willobviously (vary somewhat, depending upon the consistency of the asphaltthe rate of heat radiation from the emulsifying apparatus and thefrictional heat, developed during emulsificamo tion.v

' say 100 degrees conducted through i 'strumentality.

In the accompanying drawing, there is 2 shown a diagrammaticillustration of apparatus that may be employed in carrying out theinvention.

The base to be emulsified preferably consists of a bitumen, non-fluid atnormal temperatures, such for example as asphalt, pitches, or the like,having melting points of, to 200 degrees F. These materials areemulsified in heat liquefied condition, but as already stated, it is thepurpose of my invention to bring them to the. emulsifying bath at atemperature not more than about 50 degrees to 10(1 degrees F above themelting point thereof. In order that these materials may be convenientlyhandled and pumps from one point to another in the emulsifying plant, itis necessary that they be heated to a temperature sutliciently high forrendering them fluid enough to permit pumping through pipes, et cetera,and this temperature is generally considerably higher than that at whichit is desirable to introduce the same into the emulsifying bath. Forexample, when emulsifying asphalt of, say 140 F. melting point, ball andring method) the asphalt must be heated to about 300 to 325 F. in orderto condition it for ready handling. The asphalt may be heated to thistemperature in any convenient way, and conducted by means of pumps (notshown) through a feed line 10 to a storage tank 11. 'This asphalt maybelemulsified in an emulsifier of the general type shown at 12, whichmay consist of a cylindrical tank, within which is mounted a baffle 13concentric with and spaced from the walls of the tank and open at itsupper and lower ends;

Suitable stirring or-agitating blades 14 are fixed upon a vertical shaft15.driven from any suitable source of power, and mounted interiorly ofthe baffle so as to agitate the mass of material in the emulsifyingvessel.

The emulsifying media may be stored in a suitable receptacle emulsifyinginstrumentality through a valved pipe 17 so as to feed the suspension ofemulsifying media into the material undergoing agitation withinthebafile. The asphalt is likewise fed into the mass of material withinthe 'baflie through a feeding pipe 18, after previously having beencooled, in the manner hereinafter to be more fully described, to atemperature of about 50 F. above the temperature of the mass in theemulsifying in- The propeller or agitator blades 14 arepitched so as toforce the material imdergolng agitation within the bafiie downwardly,the material then taking an upward course in the annular space betweenthe battle and the wall of the tank 12 and being thus recirculated forfurther agitation within the bafile. "The finished emulsion may bewithdrawn from the tank 12 continuously or cooled to the desired degreeby means 0 the smaller chamber 21 and 16 and conducted to the prior tothe introduction thereof into the emulsifying instrumentality, I mayprovide an enlarged chamber 20 within which is maintained a smallerchamber 21-to which the hot asphalt may be fedfrom the storage tank 11through a valved feed pipe 22. hollow drum-or cylinder 23 is mounted forrotation in the chamber 21, the diameter of this drum or cylinder beingsuch in relation to the height of the chamber 21 that a portion only ofthe peripheral surface of the drum is submerged within the 'moltenasphalt in the chamber-during the rotation of the drum. A suitablecooling or refrigerating medium may be continuously circulated throughthe interior of the cylinder or drum 23 as by means of an inlet conduit24 and outlet conduit 25. If desired, the drum 23 may be provided withan internal concentric cylinder (not shown), and the cooling mediumcirculated through the annular space between the outer and inner drums.The drum 23 is rotated slowly and during such rotation picks up a thinfilm of the asphalt from the chamber 21, this film being ragidllly t ecooling medium circulating in the interior of the drum. A doctor bladeor apron 26 is suitably mounted so as to be in free contact with thesurface of the rotating cylinder to thereby remove the cooled asphaltcontinuously therefrom and discharge the same as shown into the enlargedchamber 20, the doctor blade for this purpose having its outer edgeextending beyond the corresponding wall of being inclined downwardly soas to permit free flow of the cooled asphalt over the surface of theblade for continuous delivery to the enlarged chamher. The flow ofasphalt from the storage tank 11 to the chamber 21 is maintained in suchratio relative to the withdrawal of the cooled asphalt from chamber 20through the pipe 18 that the level of the asphalt in the Y enlargedchamber will preferably be at all times below the bottom of the smallerchamber 21, thus avoiding material transfer of heat from the hot asphaltin the chamber 21 to the cooled asphalt in the enlarged chamber 20.For-this purpose also there may be employed,-if desired, suitable liquidlevel regudevices for the enlarged chamber20,

lating as well as for the smaller chamber 21, the

overflow being conducted to the storage tank By'the arrangement as thusdescribed, I have made it possible to emulsify bitumens or the like in abath which can be consistently maintained at temperatures approximatingthe melting point of the material to be emulsifie without substantialvariation of this LA to a su temperature due to the temperature of theincoming bitumen and without afiecting the normal plant procedureincident to the ready and convenient han and transfer of the material tobe emulsi through pumps; feed lines, et cetera.

I- claim as my invention:

tially predetermined temperature, which comprises maintaining a pool ofmolten bitumen, picking up the bitumen from said pool in a thin film andsubjecting said.

film of bitumen to a cooling media in indirect contact therewith, andcontinuously delivering said film of cooled bitumen, in a liquid state,to a bulk su Egly.

2. A process for coo g molten bitumen to a predetermined temperatureabove the melting point thereof, which comprises maintaining apool-'ofithe molten. bitumen, picking up the bitumen from said pool in athin film and subjecting said film of bitumen to a. cooling media inindirect contact therewith and continuously delivering said film ofbitumen, in a li uid state, after subjection to said cooling me um to abulk supply maintained out of contact with said pool.

In testimon whereof I aflix my si ature.

L STER KIRSCHBR UN.

rocess for cooling molten bitumen.

